Fair Value Measurements (Assets And Liabilities Measured At Fair Value) (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended |
Sep. 30, 2016 | Dec. 31, 2015 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | $ 495,171 | $ 321,743 |
Liabilities | 41,641 | 19,687 |
Held-to-maturity Securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Marketable securities, unrealized loss | 110 | 209 |
Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 493,865 | 320,607 |
Liabilities | 0 | 19,667 |
Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 164 | 0 |
Liabilities | 41,620 | 0 |
Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 1,142 | 1,136 |
Liabilities | 21 | 20 |
Cash equivalents | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 367,005 | 214,232 |
Cash equivalents | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 367,005 | 214,232 |
Cash equivalents | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 0 | 0 |
Cash equivalents | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 0 | 0 |
Short-term investments | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 126,860 | 106,375 |
Short-term investments | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 126,860 | 106,375 |
Short-term investments | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 0 | 0 |
Short-term investments | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 0 | 0 |
Interest rate swap | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 164 | |
Interest rate swap | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 0 | |
Interest rate swap | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 164 | |
Interest rate swap | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 0 | |
Auction rate securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 1,142 | 1,136 |
Auction rate securities | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 0 | 0 |
Auction rate securities | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 0 | 0 |
Auction rate securities | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets | 1,142 | 1,136 |
Long-term notes | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Liabilities | 41,620 | 19,667 |
Long-term notes | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Liabilities | 0 | 19,667 |
Long-term notes | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Liabilities | 41,620 | 0 |
Long-term notes | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Liabilities | 0 | 0 |
Contingent purchase consideration | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Liabilities | 21 | 20 |
Contingent purchase consideration | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Liabilities | 0 | 0 |
Contingent purchase consideration | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Liabilities | 0 | 0 |
Contingent purchase consideration | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Liabilities | $ 21 | $ 20 |